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nmdcat.online July 28, 2026

A medical researcher develops a toxin that specifically destroys the gap junctions in muscle tissue. Which two physiological processes would be most immediately and severely impaired?

A. Voluntary limb movement and shivering thermogenesis
B. Peristalsis in the intestines and rhythmic beating of the heart
✓
C. Postural maintenance and pupillary constriction
D. Arteriolar vasoconstriction and voluntary eye movement

📝 Explanation

Gap junctions are crucial for the rapid cell-to-cell transmission of electrical impulses in single-unit smooth muscle (responsible for peristalsis) and cardiac muscle (responsible for coordinated heartbeats). Skeletal muscles lack gap junctions and are individually innervated.

📖 Additional Information

  • Voluntary limb movement and shivering thermogenesis
  • Peristalsis in the intestines and rhythmic beating of the heart
  • Postural maintenance and pupillary constriction
  • Arteriolar vasoconstriction and voluntary eye movement

Gap junctions are crucial for the rapid cell-to-cell transmission of electrical impulses in single-unit smooth muscle (responsible for peristalsis) and cardiac muscle (responsible for coordinated heartbeats). Skeletal muscles lack gap junctions and are individually innervated.

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